A mid-wave infrared detector having a stepped hierarchical absorption structure

Abstract

The embodiment of the present application discloses a kind of middle wave infrared detector with stepped hierarchical absorption structure, the middle wave infrared detector includes successively from top to bottom: upper contact layer, barrier layer, absorption layer, lower contact layer, GaSb buffer layer and GaSb substrate;Wherein, the absorption layer includes multiple sub-absorption layers, each sub-absorption layer includes InAs / GaSb superlattice structure, and the period ratio of InAs / GaSb superlattice structure of each sub-absorption layer is different, and the thickness of each sub-absorption layer is not completely same. The material selection of absorption layer is mainly InAs / GaSb material system according to the scheme provided in the embodiment of the present application, and the absorption layer structure is optimized, the entire absorption layer is divided into multiple sub-absorption layers with different thickness and different period ratio, so that the dark current can be kept even under lower conditions, so as to improve the quantum efficiency of the detector, effectively ensure and improve the working performance of the infrared detector.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a mid-wave infrared detector with a stepped, graded absorption structure. Background Technology

[0002] Mid-wave infrared detection technology has crucial applications in both civilian and defense fields, such as environmental monitoring, ground disaster detection, gas detection, critical equipment, and reconnaissance. Compared to mercury cadmium telluride (HgCdTe) infrared detectors, antimony bromide (InAs / GaSb) type II superlattice infrared detectors offer better uniformity, lower cost, and superior performance at high temperatures. Commonly used type II superlattice materials for mid-wave infrared detectors include InAs / GaSb and InAs / InAsSb. Generally, InAs / GaSb type II superlattices offer better wavelength engineering freedom, higher carrier lifetime, lower Auger recombination rate, and wider infrared band tunability than InAs / InAsSb, making them particularly suitable for high-performance mid- and long-wave infrared detection.

[0003] However, at high operating temperatures, the high noise and short carrier lifetime result in low quantum efficiency for InAs / GaSb type II superlattice infrared detectors. Therefore, improving the quantum efficiency of the detector has become an urgent technical problem to be solved. Summary of the Invention

[0004] This application provides a mid-wave infrared detector with a stepped, graded absorption structure to improve the detector's quantum efficiency. The specific technical solution is as follows.

[0005] In a first aspect, embodiments of this application provide a mid-wave infrared detector with a stepped, graded absorption structure, wherein the mid-wave infrared detector comprises, from top to bottom: an upper contact layer, a barrier layer, an absorption layer, a lower contact layer, a GaSb buffer layer, and a GaSb substrate.

[0006] The absorption layer includes multiple sub-absorption layers, each of which includes an InAs / GaSb superlattice structure. The period ratio of the InAs / GaSb superlattice structure of each sub-absorption layer is different, and the thickness of each sub-absorption layer is not exactly the same.

[0007] In one embodiment of this application, the thickness of the absorption layer is 2μm-6μm, the doping method is p-type doping, and the doping concentration is 1×10⁻⁶. 14 -1×10 15 cm -3 .

[0008] In one embodiment of this application, the thickness of the absorption layer is 4 μm; the absorption layer includes three sub-absorption layers, and the superlattice structures of each sub-absorption layer from top to bottom are 1.5 μm 10MLInAs / 9MLGaSb, 1.5 μm 10MLInAs / 10MLGaSb, and 1 μm 10MLInAs / 16MLGaSb, respectively.

[0009] In one embodiment of this application, both the upper contact layer and the lower contact layer comprise an InAs / GaSb superlattice structure; the barrier layer comprises an InAs / AlSb superlattice structure.

[0010] In one embodiment of this application, the thickness of the lower contact layer is 1000-1500 nm, the doping method is p-type doping, and the doping concentration is 5 × 10⁻⁶. 17 -5×10 18 cm -3 .

[0011] In one embodiment of this application, the thickness of the upper contact layer is 500-1500 nm, the doping method is n-type doping, and the doping concentration is 5 × 10⁻⁶. 17 -5×10 18 cm -3 .

[0012] In one embodiment of this application, the GaSb buffer layer has a thickness of 100-1000 nm, is p-type doped, and has a doping concentration of 5 × 10⁻⁶ nm. 17 -5×10 18 cm -3 .

[0013] In one embodiment of this application, the barrier layer has a thickness of 100-500 nm, is n-type doped, and has a doping concentration of 1×10⁻⁶. 14 -1×10 15 cm -3 Furthermore, the superlattice structure of the barrier layer is 12ML InAs / 6MLAlSb.

[0014] In one embodiment of this application, the operating temperature of the mid-wave infrared detector is 150K, and the operating bias voltage of the mid-wave infrared detector is -0.2V.

[0015] In one embodiment of this application, the lower surface of the upper contact layer is bonded to the upper surface of the barrier layer; the lower surface of the barrier layer is bonded to the upper surface of the absorption layer; the lower surface of the absorption layer is bonded to the upper surface of the lower contact layer; the lower surface of the lower contact layer is bonded to the upper surface of the GaSb buffer layer; and the lower surface of the GaSb buffer layer is bonded to the upper surface of the GaSb substrate.

[0016] In this embodiment, the absorption layer is mainly composed of InAs / GaSb material system, and the structure of the absorption layer is optimized by dividing the entire absorption layer into multiple sub-absorption layers with different thicknesses and period ratios. This ensures that the dark current is maintained or even reduced, thereby improving the quantum efficiency of the detector and effectively guaranteeing and improving the working performance of the infrared detector. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This illustration shows a schematic diagram of a mid-wave infrared detector with a stepped, graded absorption structure according to an embodiment of this application.

[0019] Figure 2 The figure shows the theoretical calculation results of the quantum efficiency of the nBp device with a stepped graded absorption layer and the device with a uniform absorption layer structure provided in the embodiments of this application;

[0020] Figure 3 The diagram shows the theoretical calculation results of the dark current of an nBp device with a stepped absorption layer and a device with a uniform absorption layer structure provided in the embodiments of this application under different bias voltages.

[0021] Figure label annotations: 1 Upper contact layer, 2 Barrier layer, 3 Absorption layer, 3-1 Sub-absorption layer 1, 3-2 Sub-absorption layer 2, 3-3 Sub-absorption layer 3, 4 Lower contact layer, 5 GaSb buffer layer, 6 GaSb substrate. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] It should be noted that the terms "comprising" and "having," and any variations thereof, in the embodiments and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0024] This application provides a mid-wave infrared detector with a stepped, graded absorption structure, which can improve the detector's quantum efficiency. The embodiments of this application are described in detail below.

[0025] Figure 1 This illustration shows a schematic diagram of a mid-wave infrared detector with a stepped, graded absorption structure according to an embodiment of this application. Figure 1 As shown, the mid-wave infrared detector comprises, from top to bottom: an upper contact layer 1, a barrier layer 2, an absorption layer 3, a lower contact layer 4, a GaSb buffer layer 5, and a GaSb substrate 6; wherein, the absorption layer 3 includes multiple sub-absorption layers, each of which includes an InAs / GaSb superlattice structure, and the period ratio of the InAs / GaSb superlattice structure of each sub-absorption layer is different, and the thickness of each sub-absorption layer is not exactly the same.

[0026] Known mid-wave infrared detectors exhibit increased current and decreased carrier lifetime at high operating temperatures, resulting in low quantum efficiency. In this embodiment, to improve the quantum efficiency of the mid-wave infrared detector, the absorption layer can be configured as a stepped, hierarchical absorption structure. Specifically, the overall structure can adopt an nBp structure, meaning the upper contact layer is n-type doped, the barrier layer is p-type doped, and therefore it is called an nBp type. The absorption layer 3 can include multiple sub-absorption layers, each comprising an InAs / GaSb superlattice structure, with different period ratios and thicknesses in each sub-absorption layer.

[0027] In one implementation, the total thickness of the absorber layer 3 is 2μm-6μm, for example, 4μm, and the doping method is p-type doping with a doping concentration of 1×10⁻⁶. 14 -1×10 15 cm-3 For example, it can be 1×10 15 cm -3 .

[0028] In one implementation, the thickness of the absorption layer 3 can be 4 μm; specifically, it can include three sub-absorption layers: 3-1, 3-2, and 3-3. The superlattice structures of each sub-absorption layer from top to bottom are 1.5 μm 10ML InAs / 9ML GaSb as sub-absorption layer 3-1, 1.5 μm 10ML InAs / 10ML GaSb as sub-absorption layer 3-2, and 1 μm 10ML InAs / 16ML GaSb as sub-absorption layer 3-3.

[0029] In one implementation, both the upper contact layer 1 and the lower contact layer 4 comprise an InAs / GaSb superlattice structure; the barrier layer comprises an InAs / AlSb superlattice structure.

[0030] In one implementation, the thickness of the lower contact layer 4 is 1000-1500 nm, specifically 1500 nm, and the doping method is p-type doping with a doping concentration of 5 × 10⁻⁶. 17 -5×10 18 cm -3 For example, it can be 5×10 17 cm -3 In other words, a 1500nm InAs / GaSb under-contact layer 4 can be grown on the GaSb buffer layer 5.

[0031] In one implementation, the thickness of the upper contact layer 1 is 500-1500 nm, specifically 500 nm, and the doping method is n-type doping with a doping concentration of 5 × 10⁻⁶. 17 -5×10 18 cm -3 For example, it can be 1×10 18 cm -3 In other words, a 500nm InAs / GaSb upper contact layer 1 can be grown on the barrier layer 2. Using an InAs / GaSb superlattice structure as the contact layer, a certain bias voltage needs to be applied to collect minority carriers while satisfying lattice matching.

[0032] In one implementation, the GaSb buffer layer has a thickness of 100-1000 nm, specifically 500 nm, and is p-type doped with a doping concentration of 5 × 10⁻⁶. 17 -5×10 18 cm -3 For example, it can be 1×10 18 cm -3In other words, a 500nm GaSb buffer layer 5 can be grown on the GaSb substrate 6.

[0033] In one implementation, the barrier layer has a thickness of 100-500 nm, specifically 300 nm, and is n-type doped with a doping concentration of 1 × 10⁻⁶. 14 -1×10 15 cm -3 For example, it can be 1×10 15 cm -3 Furthermore, the superlattice structure of the barrier layer is 12MLInAs / 6MLAlSb. In other words, a 300nm superlattice structure can be grown on the absorber layer 3 as the barrier layer 2.

[0034] In one implementation, the mid-wave infrared detector provided in this embodiment operates at a temperature of 150K and has an operating bias voltage of -0.2V. Electrodes can be mounted between the lower contact layer 4 and the GaSb buffer layer 5, and above the upper contact layer 1, respectively.

[0035] In one implementation, the lower surface of the upper contact layer is bonded to the upper surface of the barrier layer; the lower surface of the barrier layer is bonded to the upper surface of the absorption layer; the lower surface of the absorption layer is bonded to the upper surface of the lower contact layer; the lower surface of the lower contact layer is bonded to the upper surface of the GaSb buffer layer; and the lower surface of the GaSb buffer layer is bonded to the upper surface of the GaSb substrate.

[0036] In this embodiment, the absorption layer is mainly composed of InAs / GaSb material system, and the structure of the absorption layer is optimized by dividing the entire absorption layer into multiple sub-absorption layers with different thicknesses and period ratios. This ensures that the dark current is maintained or even reduced, thereby improving the quantum efficiency of the detector and effectively guaranteeing and improving the working performance of the infrared detector.

[0037] Figure 2 The diagram illustrates the theoretical calculation results of the quantum efficiency of an nBp device with a stepped absorption layer and a device with a uniform absorption layer structure, as provided in the embodiments of this application. Device number 1 represents a device with a uniform absorption layer structure, and device number 2 represents an nBp device with a stepped absorption layer. Specifically, the absorption region thickness and doping concentration of device number 1 are 4 μm and 1 × 10⁻⁶, respectively. 15 cm -3 The barrier region thickness and doping concentration are 0.3 μm and 1 × 10⁻⁶, respectively. 15 cm -3 .

[0038] The absorption region numbered 2 comprises three sub-absorption layers with thicknesses of 1.5 μm, 1.5 μm, and 1 μm, respectively, all with a doping concentration of 5 × 10⁻⁶.14 cm -3 The barrier region thickness and doping concentration are 0.3 μm and 1 × 10⁻⁶, respectively. 15 cm -3 Both types of devices listed above operate at 150K with a bias voltage of -0.2V. Figure 2 It can be clearly seen that after the absorption layer of device No. 2 is designed with hierarchical absorption, the quantum efficiency is higher than that of device No. 1.

[0039] Figure 3 The diagram shows the theoretical calculation results of the dark current of an nBp device with a stepped absorption layer and a device with a uniform absorption layer structure under different bias voltages, as provided in the embodiments of this application. Figure 2 Similarly, device number 1 is a device with a uniform absorption layer structure, and device number 2 is an nBp device with a stepped, hierarchical absorption layer. Specifically, the absorption region thickness and doping concentration of device number 1 are 4 μm and 1 × 10⁻⁶, respectively. 15 cm -3 The barrier region thickness and doping concentration are 0.3 μm and 1 × 10⁻⁶, respectively. 15 cm -3 .

[0040] The absorption region numbered 2 comprises three sub-absorption layers with thicknesses of 1.5 μm, 1.5 μm, and 1 μm, respectively, all with a doping concentration of 5 × 10⁻⁶. 14 cm -3 The barrier region thickness and doping concentration are 0.3 μm and 1 × 10⁻⁶, respectively. 15 cm -3 Both of the above numbered devices operate at a temperature of 150K. As can be clearly seen from the enlarged image above, the dark current of device number 2 is slightly reduced after the absorption layer is designed with a graded absorption layer.

[0041] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application.

[0042] Those skilled in the art will understand that the modules in the apparatus of the embodiments can be distributed in the apparatus of the embodiments as described in the embodiments, or they can be located in one or more devices different from this embodiment with corresponding changes. The modules of the above embodiments can be combined into one module, or they can be further divided into multiple sub-modules.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A mid-wave infrared detector with a stepped, graded absorption structure, characterized in that, The mid-wave infrared detector comprises, from top to bottom: an upper contact layer, a barrier layer, an absorption layer, a lower contact layer, a GaSb buffer layer, and a GaSb substrate. The absorption layer includes multiple sub-absorption layers, each of which includes an InAs / GaSb superlattice structure. The period ratio of the InAs / GaSb superlattice structure of each sub-absorption layer is different, and the thickness of each sub-absorption layer is not exactly the same. The thickness of the absorption layer is 4 μm; the absorption layer includes 3 sub-absorption layers, and the superlattice structures of each sub-absorption layer from top to bottom are 1.5 μm 10ML InAs / 9ML GaSb, 1.5 μm 10ML InAs / 10ML GaSb, and 1 μm 10ML InAs / 16ML GaSb, respectively.

2. The mid-wave infrared detector according to claim 1, characterized in that, The doping mode of the absorption layer is p-type doping, and the doping concentration is 1×10 14 -1×10 15 cm -3 .

3. The mid-wave infrared detector according to claim 1, characterized in that, Both the upper contact layer and the lower contact layer comprise an InAs / GaSb superlattice structure; the barrier layer comprises an InAs / AlSb superlattice structure.

4. The mid-wave infrared detector according to claim 3, characterized in that, The lower contact layer has a thickness of 1000-1500 nm, is p-type doped, and has a doping concentration of 5 × 10⁻⁶. 17 -5× .

5. The mid-wave infrared detector according to claim 3, characterized in that, The upper contact layer has a thickness of 500-1500 nm, is n-type doped, and has a doping concentration of 5 × 10⁻⁶. 17 -5× .

6. The mid-wave infrared detector according to claim 1, characterized in that, The GaSb buffer layer has a thickness of 100-1000 nm, is p-type doped, and has a doping concentration of 5 × 10⁻⁶. 17 -5× .

7. The mid-wave infrared detector according to claim 1, characterized in that, The barrier layer has a thickness of 100-500 nm, is n-type doped, and has a doping concentration of 1×10⁻⁶. 14 -1×10 15 cm -3 Furthermore, the superlattice structure of the barrier layer is 12ML InAs / 6ML AlSb.

8. The mid-wave infrared detector according to claim 1, characterized in that, The operating temperature of the mid-wave infrared detector is 150K, and the operating bias voltage of the mid-wave infrared detector is -0.2V.

9. The mid-wave infrared detector according to claim 1, characterized in that, The lower surface of the upper contact layer is attached to the upper surface of the barrier layer; the lower surface of the barrier layer is attached to the upper surface of the absorption layer; the lower surface of the absorption layer is attached to the upper surface of the lower contact layer; the lower surface of the lower contact layer is attached to the upper surface of the GaSb buffer layer. The lower surface of the GaSb buffer layer is attached to the upper surface of the GaSb substrate.

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